1. Field of the Invention
The invention relates to clamping devices used to secure electrical devices to supporting structures or other electrical components.
2. Description of the Art
One of the most frequent uses of clamping devices in electrical arts involves clamping heat generating electrical components to a substrate. The substrate usually takes the form of a heat sink. Heat generated by the electrical devices is transferred to the heat sink where in turn it is dissipated in ambient or moving air. The supporting surface is conventionally a flat surface along which a plurality of heat generating electrical devices are spaced apart, usually in a linear fashion. A bolt or post is commonly provided extending perpendicularly from the support surface between adjacent devices to served as an attachment means for the clamping devices.
Prior art clamping devices that have been used for this purpose are rectangular pieces cut, for example, from approximately 11 gauge steel. The outer ends have formed depressions which extend below the bottom surface. An opening in the center or offset from the center between the formed depressions receives a bolt or post which connects them to the heat sink. The formed depressions are intended to rest upon the upper surface of the heat generating electrical devices. The known clamping devices are extremely rigid due to their heavy gauge steel construction. Where three electrical devices are to be positioned on the surface, two of the heavy gauge clamping devices have their edges abutted in the middle such that a formed depression on each clamp rests on a side of the device under it and not in the center. It is difficult to simultaneously provide sufficient clamping force to resist vibration and thermal effects while at the same time avoiding cracking of the electrical devices due to over torquing of the fasteners which attach and connect the clamping devices to the substrate. In addition, rigid existing clamps are ill-suited to accommodate varying heights in the electrical devices to be attached to a heat sink. Usually the thicker electrical devices are wider as well as higher which sometimes results in contact between the underside of the clamp and the edge of the larger device. This can lead to damage to the device or application of a torque to the electrical device which tends to create uneven pressure on the clamped device. It can even tend to lift one portion of the heat generating device away from the heat conducting surface which may reduce heat transfer efficiency. This problem is made worse by manufacturing variations especially when the parts come from different sources.